Correlative all-optical quantification of mass density and mechanics of sub-cellular compartments with fluorescence specificity

Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples - so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical diffraction tomography and epi-fluorescence imaging for explicitly measuring the Brillouin shift, RI and absolute density with specificity to fluorescently labeled structures. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the nucleoplasm of wild-type HeLa cells, we find that it has lower density but higher longitudinal modulus than the cytoplasm. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample - a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.

The transverse and longitudinal elastic constants of pulp fibers in paper sheets

Cellulose fibers are a major industrial input, but due to their irregular shape and anisotropic material response, accurate material characterization is difficult. Single fiber tensile testing is the most popular way to estimate the material properties of individual fibers. However, such tests can only be performed along the axis of the fiber and are associated with problems of enforcing restraints. Alternative indirect approaches, such as micro-mechanical modeling, can help but yield results that are not fully decoupled from the model assumptions. Here, we compare these methods with nanoindentation as a method to extract elastic material constants of the individual fibers. We show that both the longitudinal and the transverse elastic modulus can be determined, additionally enabling the measurement of fiber properties in-situ inside a sheet of paper such that the entire industrial process history is captured. The obtained longitudinal modulus is comparable to traditional methods for larger indents but with a strongly increased scatter as the size of the indentation is decreased further.

Mechanical and Radiation Shielding properties of CuO doped TeO2-B2O3 Glass System

A series of borotellurite glass system doped with copper oxide was synthesized using the method of melt quenching. The density of the glass decreases whereas its molar volume increases in respect to copper oxide concentration. The amorphous nature of prepared glasses was proven with the utilisation of XRD spectra. Meanwhile, the glass samples’ elastic properties are determined from the measurement of longitudinal and shear velocities using ultrasonic technique. The longitudinal modulus, shear modulus, bulk modulus and Young’s modulus will show an irregular trend that fluctuates. FLUKA Monte Carlo code is implemented to determine the shielding features at gamma energy 0.3565, 0.6616, 0.8348 and 1.3325 MeV. Linear attenuation coefficients acquired from FLUKA and XCOM are found to be in good agreement with relative difference < 1%. The glass sample B2O3TeO2CuO1 (with highest percentage of TeO2) is found to be the best shielding glass material in this study.

Comparison Study of Elastic, Physical and Structural Properties for Strontium Oxide and Manganese Oxide in Borotellurite Glasses for High Strength Glass Application

In this research the melt quenching technique method was used to synthesize two series of borotellurite glass systems doped with manganese and strontium. Elastic measurement, X-Ray Diffraction and Fourier Transform Infrared spectroscopy were used to characterize the prepared glass samples. The increment of molar volume confirmed the theory that molar volume is inversely proportional to the density parameters. A broad hump appeared in XRD as the samples shown pure amorphous nature. In FTIR, the functional group vibrations of tellurite network were recorded such as TeO4 trigonal bipyramids and TeO3 trigonal pyramids by addition of both dopants. On the other hand, ultrasonic velocity was used to determine the elastic moduli of the glass such as bulk modulus, shear modulus, longitudinal modulus, Young’s Modulus, microhardness and Poisson’s ratio which showed decreasing and increasing trends with the increased concentration of MnO2 and SrO respectively.

Dielectric and mechanical properties of nickel silica core-shell reinforced PMMA nanocomposites

This paper study the dielectric and mechanical properties of poly (methyl methacrylate)-nickel silica core-shell nanocomposite. Ni@SiO2/PMMA nanocomposite films were prepared by incorporating Ni@SiO2 nanoparticles in PMMA matrix using the solution casting method. The morphology of the prepared nanoparticles was examined through a High-resolution transition electron microscope (HRTEM), which revealed the formation of SiO2 shell at Ni magnetic nanoparticles. The dielectric properties of the nanocomposite films were studied as a function of temperature and frequency in the ranges of 30–180°C and 100 Hz – 5 MHz respectively. The incorporation of the nano Ni@SiO2 to PMMA has a positive effect on the dielectric constant ε′ of the nanocomposites, as well as, ε′ improved with increasing temperature. The real electric modulus (M′) of composites confirms the occurrence of dispersion in all composites at all temperatures. While dielectric loss tangent ε ″ and the loss part of electric modulus spectra (M) exhibit relaxation peaks which characterize possible relaxation of interfacial polarization in the interface between Ni@SiO2 core-shell and PMMA matrix, these peaks have shifted towards higher frequency with temperature. The relaxation and activation energies, Ec and Ea values decreased from 0.49 to 0.40 eV and from 0.87 to 0.70 eV respectively as Ni@SiO2 content increased. The ac conductivity of the nanocomposite films has deeply increased with increasing temperature and Ni@SiO2 content. The longitudinal modulus (L), shear modulus (G), Young's modulus (E), and bulk modulus (B) of films were studied and they increased as the filler increased from 0 to 15 wt.%.

Research into the Effect of Grain and the Content of Alundum on Tribological Properties and Selected Mechanical Properties of Polymer Composites

The subject of the research is a polymer composite with a matrix base of epoxy resin L285 cured with H285 hardener, and a physical modifier of friction in the form of alundum. The article presents an analysis of findings of tribological examinations. The authors evaluated the influence of the modifier properties in the form of alundum, i.e., mass share and grain size, on the abrasive wear of a composite, defined as loss of weight as well as on roughness parameters and selected mechanical properties. The tribological examinations have been extended by measurements of hardness and density of the prepared composites. The obtained results of tribological examinations showed an increase in the average value of weight loss in relation to the loss of sample weight loss between the cycles. The influence of both the grain size and the mass percentage share of alundum upon the increase in the longitudinal modulus of elasticity was also observed. On the basis of the obtained results, it was found that alundum of grain sizes equal to F220 and F240 exerted the best influence on the reduction of abrasive wear of the tested samples. In the case of F220, it was 14.04% of the average value of the weight loss between the cycles for all percentage shares of the used grains.

Research on Improving the Welding Behaviour of Stainless Steels in the Field of Welded Constructions by Using Mechanical Vibrations

This paper presents a research that has been done on two types of stainless steels, one of Spanish origin and the other of Romanian origin. Both Spanish and Romanian stainless steels have been subjected to several tests, regarding the influence of vibrations on their mechanical properties and their welding behavior. The samples were made of welded stainless steels. They were subjected to a thermal hardening treatment at a temperature of 950 degrees, with a holding time of 4 hours in the presence of mechanical vibrations. Then comparative tests were performed on both stainless steels at: hardness, tensile test, resilience, microstructural analysis and determination of the longitudinal modulus of elasticity. The research has shown a reduction of the thermo-mechanically influenced area, which contributes to the achievement of a high quality welded joints.

Mixed-Alkali Effect in Borate Glasses: Thermal, Elastic, and Vibrational Properties

When oxide glasses are modified by dissimilar alkali ions, a maximum in the electric resistivity or the expansion coefficient appears, called the mixed-alkali effect (MAE). This paper reviews the MAE on the thermal, elastic, and vibrational properties of the mixed-cesium lithium borate glasses, x{(1−y)Cs2O-yLi2O}-(1−x)B2O3. For the single-alkali borate glasses, xM2O(1−x)-B2O3 (M = Li, Na, K, Rb, and Cs), the glass transition temperature, Tg = 270 °C, of a borate glass monotonically increases as the alkali content x increases. However, for the mixed-cesium lithium borate glasses the Tg shows the minimum against the lithium fraction y. The dependences of the elastic properties on the lithium fraction y were discussed regarding the longitudinal modulus, Poisson’s ratio, and Cauchy-type relation. The internal vibrational bands related to the boron-oxide structural groups and the splitting of a boson peak were discussed based on Raman scattering spectroscopy. The MAE on various physical properties are discussed on the basis of the changes in the coordination number of the borons and the nonbridging oxygens caused by the dissimilar alkali ions.

A numerical study of the influence of Z-pin parameters on the elastic properties of laminates

A finite element model with periodic boundary conditions was developed to investigate the influence of different Z-pin parameters including diameter, spacing, and insertion angle of Z-pin on the elastic properties of composite laminates. Benchmark tests were carried out to verify the FE model and a series of parametric analyses were subsequently performed. In general, all the elastic moduli, excluding the through-thickness modulus ( Ez), decreased while Ez increased nonlinearly with increasing Z-pin diameter and decreasing spacing. The reduction of Ey (transverse modulus) was approximately 40% of that of Ex (longitudinal modulus), while the reduction of Gxy is similar to that of Ex. Besides, Gxz and Gyz were reduced by approximately half of the reduction of Gxy. Although the impact of insertion angle was obvious on Ez, it was negligible on the other five moduli.